1. Field of the Invention
This invention relates to novel phthalocyanine compounds, a method of producing the compounds, and near infrared ray (IR) absorption materials having a high solubility in solvents. The novel phthalocyanine compounds according to the present invention have an absorption in a near IR band of 600 to 1,000 nm, have an excellent solubility, and have an excellent light-fastness which is inherent to phthalocyanines. Therefore, the novel phthalocyanine compounds of the present invention provide an excellent effect when used for near IR absorption pigments for writing and reading signals in optical recording media using a semiconductor laser, liquid crystal display devices, optical character readers, etc.; near IR sensitizers; light-heat conversion agents in heat-sensitive transfer, heat-sensitive paper, heat-sensitive mimeographic plate, etc.; near IR absorption filters; asthenopic inhibitors; and photo-conductor materials. Furthermore, these phthalocyanine compounds exhibit excellent effects when used for photosensitive pigments for curing tumors, having a high texture transmissibility and a high absorption of rays of light in a long wavelength band, or for heat ray shielding materials for automobiles and building materials.
Furthermore, the novel phthalocyanine compounds of the present invention exhibit excellent effects as visible ray absorbing materials such as color separation filters for use in imaging tubes, liquid crystal devices, pigments for selective absorption filters of color cathode-ray tube (CRTs), color toners, inks for ink jet, bar code inks for preventing fake, and so forth.
2. Description of the Related Art
Recently, semiconductor lasers have been used as a light source for writing and reading signals in optical recording media such as compact disks, laser disks, optical memory devices, optical cards, etc., liquid crystal display devices, optical character readers, and so forth. Therefore, demands are increasing for materials absorbing near infrared rays (IR), or "near IR absorption pigments", which are used for photoconductor materials, near IR absorption filters, asthenopic inhibitors, light-heat conversion agents in heat-sensitive transfer, heat-sensitive paper, heat-sensitive mimeographic plate, etc., near IR sensitizers, photo-sensitive pigments for curing tumors, having a high texture transmissibility and a high absorption of rays of light in a longwave band, or heat ray shielding materials for automobiles and building materials. Among them, intensive studies have been made on phthalocyanine type compounds which are stable to light, heat, temperature, etc., and have a high fastness, to control their absorption wavelengths in accordance with intended applications, or to dissolve them in solvents in accordance with the intended applications.
As devices have become diversified in recent years, pigments having various absorption characteristics in accordance with applications have been desired. Nevertheless, it has been difficult to control the absorption wavelengths of the phthalocyanine type compounds. The pigments must be converted to a thin film without complicated steps such as vacuum evaporation or dispersion in a solvent, and in this case, a solvent which does not corrode substrates used for the devices must be used. Furthermore, the pigments must be dissolved in the resins used therewith. For these reasons, pigments capable of being dissolved in high concentrations in a variety of solvents in accordance with the applications have been required, but most of the phthalocyanine type compounds are insoluble in solvents.
Phthalocyanine compounds having solubility, which may be advantageous from the aspect of practical application, are disclosed recently. For example, 3,6-octaalkoxyphthalocyanine is known from Japanese Unexamined Patent Publication (KOKAI) No. 61-223056, but this compound involves problems such that control of the absorption wavelength is limited to a low wavelength side, and that an economical phthalocyanine cannot be obtained because the production process is complicated.
Japanese Unexamined Patent Publication (KOKAI) Nos. 60-209583, 61-152685, 63-308073 and 64-62361 disclose those compounds which improve solubility, and at the same time, expand the absorption wavelength to a longer wave length side by introducing a large number of thioether groups into the phthalocyanine skeletal structure for substitution. Among them, Japanese Unexamined Patent Publication (KOKAI) Nos. 60-209583 and 61-152685 disclose synthesis examples wherein the thioether groups are introduced into the phthalocyanine skeletal structure, particularly into the 3,6-positions. This method obtains the phthalocyanine compound having the thioether group at the 3,6-positions by heating a phthalocyanine compound having chlorine atoms at the 3,6-positions of the phthalocyanine skeletal structure and an organic thiol compound in a quinoline solvent in the presence of KOH. Since the yield is as low as about 20% to about 30%, however, this method has a problem of a poor production efficiency. Moreover, the solubility is still insufficient and the range of the absorption wavelength is limited.
Japanese Unexamined Patent Publication (KOKAI) Nos. 60-209583, 61-152685 and 64-62361 disclose Synthesis Examples wherein eight to sixteen thioether groups are introduced into the phthalocyanine skeletal structure.
This method obtains phthalocyanine having eight to sixteen thioether groups at the benzene ring of the phthalocyanine skeletal structure by heating a phthalocyanine compound having eight to sixteen chlorine and/or bromine atoms at the benzene ring of the phthalocyanine skeletal structure with an organic thiol compound in a quinoline solvent in the presence of KOH. The yield, however, is from about 20% to about 30% and the problem of a poor production efficiency remains unsolved, in the same way as described above.
Namely, since the substitution efficiency of the chlorine or bromine atoms to the thioether groups is low, the production yield becomes low, as well. Accordingly, an unreacted phthalocyanine in which the thioether groups have not been substituted with the chlorine atoms, or an unreacted phthalocyanine in which the thioether groups have been partially substituted with chlorine atoms, is generated. It is practically difficult to separate these unreacted phthalocyanine compounds from an intended phthalocyanine compound. For this reason, substantially only phthalocyanine mixtures having various compositions can be obtained.
Further, Japanese Unexamined Patent Publication (KOKAI) No. 64-62361 describes compounds as "polythiol substitution, mixed, condensed type phthalocyanine composition" even after separation using a silica gel, and admits that unreacted compounds remain. If a part of the chlorine atoms are left, solubility drops remarkably, and this leads to the drawback that the pigment cannot be easily dissolved and converted to a thin film as an IR absorption pigment, or other uses such as visible light absorption filter.
The method described in Japanese Unexamined Patent Publication (KOKAI) No. 63-308073 obtains a phthalocyanine compound at a yield of 42% by heating monobromotetradecachlorophthalocyanine and an organic thiol mixture comprising 2-aminothiophenol and 4-methylphenylthiol in a DMF solvent in the presence of KOH. Since in this method different organic thiol mixtures are simultaneously added and reacted, however, a resulting phthalocyanine mixture comprises phthalocyanines having different combinations of substituents, and therefore homogeneous product cannot be obtained. Accordingly, the application of the reaction product to those applications requiring the control of the absorption wavelength, such as the use as ink for cyan color ink jet, or as a near IR absorption pigment, is limited, for example. Although the reaction product has a solubility, its solubility is not yet sufficient for thin film formation or for dissolution in a resin.
Japanese Unexamined Patent Publication (KOKAI) Nos. 64-42283 and 3-62878 propose near IR absorption pigments having alkoxyl groups and alkylthio groups introduced into the phthalocyanine nucleus. Nevertheless, since most of these products are derived from starting materials having the substituent groups at the 3,6-positions, which have low practical utility, they involve the problem of practical applicability. The solubility of the product remains at a low level, and there is a limit to the derivation of phthalocyanines having controlled absorption wavelengths. To introduce the substituent groups into the 4,5-positions, the reference methods derive phthalocyanines from the starting materials in which the 4,5-positions are chlorinated. Accordingly, due to this low substitutivity, chlorine atoms, as a factor lowering the solubility, remain in the product.
Further, phthalocyanines soluble in alcohols are described in Japanese Unexamined Patent Publication (KOKAI) No. 63-295578. According to this reference, substituted thiocopper phthalocyanine mixtures obtained by reacting monobromo-tetradecachlorocopper phthalocyanine with an organic thiol mixture consisting of 2-aminothiophenol and 4-methylphenylthiol, such as hepta(4-methylphenylthio)-tetra(1-amino-2-thiophenyl-1,2-ylen)-copper phthalocyanine, is sulfonated by fuming sulfuric acid to obtain a phthalocyanine having ten sulfonic acid groups on an average, and the reaction product is then treated with a basic material such as tetrabutylammonium salt to convert them to sulfonamide groups, etc., and thus phthalocyanines having solubility in alcoholic solvents are obtained.
This method, however, involves the following problems.
The chlorine atoms are likely to partially remain, and if they remain, the solubility of the compounds drops remarkably.
Phthalocyanines are obtained as a mixture, and when the mixture is used as the near IR absorption pigment, the uniform characteristics cannot be obtained. Therefore, its application is limited.
The production process is extremely complicated, and the yield at each production step is low.
Since the sulfonation reaction is carried out in an aqueous system and then, the reaction product is purified by dialysis, this method involves the problems yet to be solved as an industrial production method.
To solve these problems, in Japanese Patent Application Nos. 1-209599, 2-125518 and 2-144292, the inventors of the present invention attempted to extend the absorption to a longer absorption wavelength and to improve solubility in solvents by selectively replacing fluorine atoms of octadecafluoropphthalocyanine with alkylthio groups or arylthio groups, and obtained certain effects. However, compounds having higher solubility are desired and an absorption wavelength, too, is desired to be extended to a longer wavelength.